I'm new to LDAP. I got an address book working, and it works fine.
I was wondering if it is possible from one subtree to link to another
subtree in the hierarchical database, so that the same data can be found
under more the one subtree?

Maybe you want to look at "referrals", or maybe just the "seeAlso"
attribute.

If i am right, seeAlso is just a reference to another entry in the LDAP
tree. Referrals are used to split up the ldap-tree on more than one
server, so that every server handles only the queries for a piece of the
tree.

What I'd like to do is the following. Every subtree contains a set of
entries. So a person with a search base dc=f1, dc=dm, dc=tld can see
the entries under dc=f1,dc=dm,dc=tld. A person with searchbase dc=f2,
dc=dm, dc=tld can see other entries...
I would like to put common entries under the tree dc=common,dc=dm,dc=tld
and make that every person how searches his searchbase can see all
entries under his searchbase and also those under the 'common' tree.